Though white is traditional, using other colors for your underbases can help you create incredible designs on dark garments.
3. Next, create the information for the other channels. You do this by duplicating the original file again, converting the background to white, and then changing your image to CMYK mode with the Maximum Black setting turned on. I find that doing these types of underbases in CMYK rather than using Color Range gives the overprint colors a desirable gloss, more like an oil painting than a solid spot color. Edit your CMYK properties first: Edit/Color Settings/CMYK; select Custom CMYK, and change black to maximum, as shown in Figure 4 (left).
4. Once your duplicate file is converted to maximum black CMYK, copy and paste just the cyan, yellow, and black channels into the “blue,” “yellow,” and “black” separation channels in your original design. (See Figure 5, right.)
5. Delete the copy of your original file to avoid confusion and then edit the copied channels to boost color and remove any ghosted areas using the Curves menu on each separation channel (Control/Command-M). Finalize the design using the Color Range tool with the background temporarily converted to black to select your highlight white channel. (See Figure 6, left.)
6. The final step is to convert all your Alpha Channels in Channel Options to match the ink color you will print. (You can use Color Picker for this or a PMS color match from the library.) Change the Alpha Channel to Spot Color and the opacity to 6 percent for the top color channels and around 80 percent for the underbase channel. You can then turn on the “eye” in front of each channel in the same order as the print sequence you are planning and view a digital approximation of how your separation will print. This won’t be a perfect match, but it will give you an idea if there are any bad areas or spots where the underbase is showing. You can view your design in stages with each color turned on in sequence to catch errors and see if the alternate underbase appears to be working. (See Figure 7, below.)
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